This invention relates to an easy to clean, round cylindrical, white plastic birdhouse, especially for colonies of purple martins. The birdhouse consists of two main parts: an outer shell fitting over and enclosing an inner core of nesting compartments. The birdhouse sits atop a segmented pole, which is raised and lowered by use of an air compressor making the birdhouse easily accessible.
Many bird enthusiasts seek to encourage the native bird species of purple martins to take up residence in their neighborhoods by erecting birdhouses on poles. Purple martins are especially desired since their diet consists mainly of flying insects such as mosquitoes, wasps, flies and beetles. Early Native Americans hung dried gourd birdhouses to encourage purple martins to take up residence and eat the flying insects in the area.
Purple martins are migratory birds that winter in South America. When spring arrives in the United States in areas east of the Rocky Mountains, the purple martins migrate north to feast on flying insects and begin nest building. Many bird enthusiasts track the large flocks of northbound migrating purple martins along their flight path. Purple martin scouts lead the way and seek out the best nesting sites. However, other bird species, such as barn sparrows and starlings, can arrive before the purple martins and claim all nesting sites, thereby forcing the purple martins to look elsewhere. It becomes crucial to have a birdhouse or nesting compartment clean and free of other birds at the time the purple martin arrives in order to attract them to the desired location.
Purple martins are social birds that prefer to live in colonies with close proximity to humans. A traditional birdhouse with room for one nest would not be a desirable location for a purple martin. U.S. Pat. No. 4,442,793 by Overpeck describes a single nest birdhouse. An apartment style birdhouse with numerous nesting compartments would more readily attract purple martins to your backyard. U.S. Pat. No. 6,009,837 by McClasky, U.S. Pat. No. 3,804,066 by Lowe, U.S. Pat. No. 3,792,685 by Wiener and U.S. Pat. No. 4,702,198 by Holyoak describe colony type birdhouses or multi-dwelling birdhouses. The purple martin birdhouses featured in Birdhouses and Feeders You Can Make by Gerhards, 1999, and Making Fancy Birdhouses and Feeders by Self, 1988, also show multi-dwelling compartments. However, the shape of most of these birdhouses is along the more traditional style with square sides and edges and a typical pointed roof U.S. Pat. No. 3,696,792 by Bruhns is another multi-dwelling birdhouse with flat sides and a pointed roof. The shapes and styles and colors of these birdhouses are meant to blend in with the human neighborhood, to look like the house of a human. The Holyoak colony birdhouse has a cylindrical shape.
To attract purple martins to your backyard, it is important to build a house that suits the birds and yet makes it easy for humans to maintain the birdhouse on behalf of the birds. The male martin will arrive first and show off his feathers to attract the female martin to a suitable nest. In a colony birdhouse the male martin will protect two or three adjacent nesting compartments. The male martin wants to attract many females until one female chooses one of his guarded nesting compartments. Even after the female has started nest building in one of the sites, the male martin still protects adjacent nesting compartments. The male martin will also build a partial nest in one of the adjacent sites. The adult purple martins will use the adjacent nest site when the offspring grow and make the initial nest site too crowded. The flat sides of a traditional colony birdhouse make it easier for a male martin to protect two or three nesting compartments. When a male martin protects empty nest sites it reduces the number of active nests and the number of fledglings produced.
It is also critically important that the purple martin birdhouse be orientated to the same compass direction each season as in the original position. This will ensure that the purple martin can locate the same birdhouse used on a previous visit.
Both the McClasky patent and the Bruhns patent, mentioned above, incorporate a telescoping pole as part of their birdhouse patents. U.S. Pat. No. 5,540,017 by Eilam describes a telescoping flagpole that could be used as a pole for a birdhouse. U.S. Pat. No. 4,357,860 by Krzak describes a horizontal telescoping conduit using pressurized air to lengthen a cylinder.
There are a number of disadvantages in all of the above mentioned birdhouses and telescoping poles.
(1) Birdhouses that have flat sides can blunt the wind and therefore be more vulnerable to being blown down in a spring or summer storm. The flat sides make it easier for the male martin to protect more than two empty nest sites. This will reduce the number of potential martins to the colony.
(2) Birdhouses made totally of wood or metal or having wood or metal parts are apt to rot or rust and be expensive to replace. Even those birdhouses with parts that are wood or metal will face deterioration of important features.
(3) Most current patented birdhouses may need annual painting to keep them blending in with the human neighborhood.
(4) Birdhouses that have numerous parts make it more difficult for the enthusiast to erect the house, maintain the house and close the house down over the winter.
(5) The square edges of most traditional looking birdhouses provide an angle for a predator squirrel to use as a lever to withdraw eggs or fledglings from a nest.
(6) Telescoping poles can be difficult for a bird enthusiast to raise and lower. The weight of a colony birdhouse can be heavy and difficult to raise manually as it requires some strength. Telescoping poles that are lowered too quickly, by the weight of the birdhouse, can cause fingers to be pinched in the segmented parts of a telescoping pole. A colony birdhouse being lowered too quickly can also knock against the head or face or eyes of a person trying to close the birdhouse down for the winter.
(7) If the nesting compartment entrances are not aligned in the same direction as when the purple martins originally used them, it can decrease the chance that the birds will return to the same location the following season.